CN110763899A - Method and device for compensating harmonic voltage measurement error of Capacitor Voltage Transformer (CVT) - Google Patents

Method and device for compensating harmonic voltage measurement error of Capacitor Voltage Transformer (CVT) Download PDF

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CN110763899A
CN110763899A CN201911011416.2A CN201911011416A CN110763899A CN 110763899 A CN110763899 A CN 110763899A CN 201911011416 A CN201911011416 A CN 201911011416A CN 110763899 A CN110763899 A CN 110763899A
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cvt
harmonic
harmonic voltage
compensating
voltage
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于波
张建宇
张海江
陈龙
李莉
茹欣
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Jiangsu Atrend High-Tech Inc Co
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Jiangsu Atrend High-Tech Inc Co
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only

Abstract

The invention provides a method and a device for compensating harmonic voltage measurement errors of a Capacitor Voltage Transformer (CVT), which comprises the following steps: (1) establishing a CVT equivalent circuit model: converting the CVT into a corresponding equivalent circuit model; (2) calculating a transfer function: based on the CVT equivalent circuit model, calculating equivalent impedance values of ports of all levels step by step, further calculating to obtain a transfer function, and obtaining frequency characteristics; (3) and (3) compensating the measurement error: according to the frequency characteristic of the CVT, the harmonic wave measurement result of the CVT is correspondingly compensated. The invention also provides a harmonic voltage measurement error compensation device of a Capacitor Voltage Transformer (CVT), which is used for completing the realization of the method and simultaneously deriving the compensated monitoring data. The invention solves the problem of large measurement error of CVT harmonic voltage and improves the accuracy of CVT harmonic voltage measurement.

Description

Method and device for compensating harmonic voltage measurement error of Capacitor Voltage Transformer (CVT)
Technical Field
The invention relates to the technical field of power system monitoring, in particular to a method and a device for compensating harmonic voltage measurement errors of a Capacitor Voltage Transformer (CVT).
Background
In power systems, voltage measurement is an indispensable basic parameter measurement. Voltage transformers can be classified into two categories, electromagnetic and capacitive, according to the working principle. At first, most buses of 110-220 kV-class power station booster stations and step-down substations adopt electromagnetic voltage transformers (abbreviated as TVs) as devices for measuring voltage and power, but the electromagnetic voltage transformers have inherent defects, such as easy ferromagnetic resonance with line distributed capacitance, capability of only measuring voltage, power and power generation protection, and the like, and although many modifications are made, accidents are still not avoided. And with the increase of the transmission voltage of the power system, the volume of the TV is larger and higher, and the cost is higher and higher. Under the requirement, a Capacitor voltage transformer (CVT for short) is researched and developed in the fifties of the last century, is built on the basis of an original Capacitor bushing voltage extraction device, can be used for voltage measurement, high-frequency communication and relay protection of a neutral point direct grounding system of 110kV or above, and is widely applied to buses of a booster station and a step-down transformer substation of a power plant in a power system.
At present, a capacitor voltage transformer (CVT for short) adopted in a high-voltage power grid can completely meet the requirements of a system in the measurement of fundamental voltage, system protection and fundamental signal conversion of an automatic device. However, the CVT in a system with harmonic components cannot correctly reflect the actual situation, and when the power quality harmonic of the system is measured, a large error exists in the secondary side signal obtained by the CVT conversion device. In appendix D of the Power quality Utility grid harmonic GB/T14549 + 1993, a method for measuring harmonics, a data processing and measuring instrument (supplement) says: the "capacitive voltage transformer cannot be used for harmonic measurement. In harmonic voltage measurement, when there is a high need for the harmonic order or measurement accuracy, a resistive voltage divider or a capacitive voltage divider "should be used. Therefore, how to master the correct power grid harmonic level and the exact voltage distortion data through the CVT test becomes the focus of attention of power grid power quality supervision technicians, and is also the first problem to be solved.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method and a device for compensating a harmonic voltage measurement error of a Capacitor Voltage Transformer (CVT), which realize the compensation of the CVT harmonic voltage measurement error, solve the problem of large CVT harmonic voltage measurement error and improve the CVT harmonic voltage measurement accuracy.
The technical scheme adopted by the invention is as follows:
the invention provides a method and a device for compensating harmonic voltage measurement errors of a Capacitor Voltage Transformer (CVT), which comprises the following steps:
s1, establishing a CVT equivalent circuit model: converting the CVT into a corresponding equivalent circuit model;
s2, calculating a transfer function: based on the CVT equivalent circuit model, calculating equivalent impedance values of ports of all levels step by step, further calculating to obtain a transfer function, and obtaining frequency characteristics;
s3, compensating measurement errors: according to the frequency characteristic of the CVT, the harmonic wave measurement result of the CVT is correspondingly compensated.
Further, in step S2, the specific calculation steps of the transfer function are as follows:
1) calculating the equivalent impedance of each stage of port as shown in formula (1):
Figure DEST_PATH_IMAGE002
Figure DEST_PATH_IMAGE004
Figure DEST_PATH_IMAGE006
（1）
Figure DEST_PATH_IMAGE008
Figure DEST_PATH_IMAGE010
Figure DEST_PATH_IMAGE012
2) based on the voltage division relation of the voltage on the series impedance, the transfer function of the voltage of each stage is listed as shown in formula (2):
Figure DEST_PATH_IMAGE014
Figure DEST_PATH_IMAGE016
（2）
Figure DEST_PATH_IMAGE020
Figure DEST_PATH_IMAGE022
Figure DEST_PATH_IMAGE024
in the formula:is the primary side voltage of the CVT;
Figure DEST_PATH_IMAGE028
is the secondary side voltage;
Figure DEST_PATH_IMAGE030
the transformation ratio of the intermediate transformer is set;
Figure DEST_PATH_IMAGE032
，
Figure DEST_PATH_IMAGE034
is the angular frequency;
Figure DEST_PATH_IMAGE036
i.e. the frequency characteristic represented by the transfer function.
Further, in step S3, the specific method for compensating the measurement error is as shown in formula (3):
Figure DEST_PATH_IMAGE038
（3）
Figure DEST_PATH_IMAGE040
in the formula:
Figure DEST_PATH_IMAGE042
the voltage amplitude of a certain harmonic wave after compensation;actually measuring the voltage amplitude for a certain harmonic wave field;
Figure DEST_PATH_IMAGE046
is the distortion ratio of certain harmonic amplitude of CVT;
Figure DEST_PATH_IMAGE048
the phase angle of a certain harmonic voltage after compensation;
Figure DEST_PATH_IMAGE050
actually measuring a voltage phase angle for a certain harmonic wave on site;
Figure DEST_PATH_IMAGE052
is a voltage phase angle deviation of a certain harmonic of the CVT.
Another object of the present invention is to provide a Capacitance Voltage Transformer (CVT) harmonic voltage measurement error compensation apparatus, which integrates a compensation method to realize CVT harmonic voltage measurement error compensation and derive compensated monitoring data.
Compared with the prior art, the invention has the following advantages and effects:
1. the invention provides a method for compensating harmonic voltage measurement errors of a Capacitor Voltage Transformer (CVT), which is rigorous in theory, completely separated from a simulation environment and convenient for practical engineering application;
2. the invention also provides a device for compensating harmonic voltage measurement errors of the Capacitor Voltage Transformer (CVT), which can realize the method and derive the compensated measurement data, thereby providing an accurate data base for power quality analysis.
Drawings
FIG. 1 is a flow chart of a compensation method;
FIG. 2 is a schematic structural diagram of a compensation device;
FIG. 3 is a schematic diagram of an equivalent circuit model of a CVT;
fig. 4 is a graph of the harmonic frequency characteristic of the present invention.
The specific implementation mode is as follows:
the present invention will be described in detail with reference to examples.
The present embodiment aims to provide a method and an apparatus for compensating a harmonic voltage measurement error of a Capacitor Voltage Transformer (CVT), so as to compensate the CVT harmonic voltage measurement error, and the method and the apparatus are specifically implemented as follows:
s1, as shown in fig. 3, establishing a CVT equivalent circuit model: converting the CVT into a corresponding equivalent circuit model;
s2, calculating a transfer function: based on the CVT equivalent circuit model, calculating equivalent impedance values of ports of all levels step by step, further calculating to obtain a transfer function, and obtaining frequency characteristics;
the specific calculation steps of the transfer function are as follows:
1) calculating equivalent impedance of each stage port
Figure DEST_PATH_IMAGE053
Figure DEST_PATH_IMAGE004A
Figure DEST_PATH_IMAGE008A
Figure DEST_PATH_IMAGE010A
Figure DEST_PATH_IMAGE012A
2) Based on the voltage division relation of the voltage on the series impedance, the transfer function of the voltage of each stage is listed
Figure DEST_PATH_IMAGE014A
Figure DEST_PATH_IMAGE016A
Figure DEST_PATH_IMAGE018A
Figure DEST_PATH_IMAGE020A
Figure DEST_PATH_IMAGE022A
In the formula:is the primary side voltage of the CVT;
Figure DEST_PATH_IMAGE028A
is the secondary side voltage;
Figure DEST_PATH_IMAGE030A
the transformation ratio of the intermediate transformer is set;
Figure DEST_PATH_IMAGE032A
，
Figure DEST_PATH_IMAGE034A
is the angular frequency;
Figure DEST_PATH_IMAGE036A
i.e. the frequency characteristic represented by the transfer function.
The resulting frequency characteristics are shown in fig. 4.
S3, compensating measurement errors: according to the frequency characteristic of the CVT, the harmonic wave measurement result of the CVT is correspondingly compensated.
Figure DEST_PATH_IMAGE038A
Figure DEST_PATH_IMAGE040A
In the formula:
Figure DEST_PATH_IMAGE042A
the voltage amplitude of a certain harmonic wave after compensation;
Figure DEST_PATH_IMAGE044A
actually measuring the voltage amplitude for a certain harmonic wave field;
Figure DEST_PATH_IMAGE046A
is the distortion ratio of certain harmonic amplitude of CVT;the phase angle of a certain harmonic voltage after compensation;
Figure DEST_PATH_IMAGE050A
actually measuring a voltage phase angle for a certain harmonic wave on site;
Figure DEST_PATH_IMAGE052A
is a voltage phase angle deviation of a certain harmonic of the CVT.
In this embodiment, the Capacitance Voltage Transformer (CVT) harmonic voltage measurement error compensation apparatus may implement the above compensation method, and derive the compensated monitoring data.
Finally, it should be noted that the above-mentioned examples, although describing particular embodiments in conjunction with the drawings, are not intended to limit the implementation of the present invention, and those skilled in the art who refer to the above-mentioned examples may modify or replace the particular embodiments of the present invention without inventive step, without departing from the spirit of the present invention, which is within the scope of the claims.

Claims (4)

1. A method and a device for compensating harmonic voltage measurement errors of a Capacitor Voltage Transformer (CVT) are characterized by comprising the following steps:
s1, establishing a CVT equivalent circuit model: converting the CVT into a corresponding equivalent circuit model;
s2, calculating a transfer function: based on the CVT equivalent circuit model, calculating equivalent impedance values of ports of all levels step by step, further calculating to obtain a transfer function, and obtaining frequency characteristics;
s3, compensating measurement errors: according to the frequency characteristic of the CVT, the harmonic wave measurement result of the CVT is correspondingly compensated.
2. The method and apparatus for compensating for harmonic voltage measurement errors in a Capacitor Voltage Transformer (CVT) as recited in claim 1 wherein said frequency characteristics comprise a 2-50 harmonic voltage magnitude and a 2-50 harmonic voltage phase angle at said step S2.
3. The method and apparatus for compensating for harmonic voltage measurement errors in a Capacitor Voltage Transformer (CVT) as recited in claim 1 wherein said step S3 compensates for measurement errors in harmonic voltage amplitudes from 2 to 50 and harmonic voltage phase angles from 2 to 50.
4. A method and apparatus for compensating for harmonic voltage measurement errors in a Capacitor Voltage Transformer (CVT) as in claim 1 wherein the apparatus is adapted to implement the method and derive the compensated monitoring data.
CN201911011416.2A 2019-10-23 2019-10-23 Method and device for compensating harmonic voltage measurement error of Capacitor Voltage Transformer (CVT) Pending CN110763899A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112345994A (en) * 2020-10-29 2021-02-09 国网新疆电力有限公司喀什供电公司 CVT harmonic measurement error self-calibration system based on cloud platform and calibration method thereof
CN112698260A (en) * 2020-11-24 2021-04-23 国网河北省电力有限公司电力科学研究院 CVT voltage sag measurement error correction method and system
CN113671245A (en) * 2021-08-18 2021-11-19 国网陕西省电力公司电力科学研究院 Digital interface with built-in time domain integration function and time domain next-time voltage acquisition method
AT525068B1 (en) * 2021-08-20 2022-12-15 Omicron Electronics Gmbh Method and device for testing a voltage converter

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112345994A (en) * 2020-10-29 2021-02-09 国网新疆电力有限公司喀什供电公司 CVT harmonic measurement error self-calibration system based on cloud platform and calibration method thereof
CN112698260A (en) * 2020-11-24 2021-04-23 国网河北省电力有限公司电力科学研究院 CVT voltage sag measurement error correction method and system
CN113671245A (en) * 2021-08-18 2021-11-19 国网陕西省电力公司电力科学研究院 Digital interface with built-in time domain integration function and time domain next-time voltage acquisition method
AT525068B1 (en) * 2021-08-20 2022-12-15 Omicron Electronics Gmbh Method and device for testing a voltage converter
AT525068A4 (en) * 2021-08-20 2022-12-15 Omicron Electronics Gmbh Method and device for testing a voltage converter

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Application publication date: 20200207